NOZZLE AND METHOD OF BLOWING HOT METAL

Abstract: An annular nozzle for an oxygen lance, e.g. an oxygen lance for blowing steel in a converter, gives an annular hot spot on the liquid steel in the converter. When exiting the nozzle, the annular jet has disruptions that result in ambient atmosphere being sucked in towards the centre of the annular jet. Thus, a sub-pressure is prevented which would otherwise prevent the jet from diverging conically. In one embodiment, the nozzle can be switched during a blowing operation between forming a tight jet and forming a diverging jet.

Description: Nozzle and method of blowing hot metal This invention relates to a supersonic annular nozzle and to a method of blowing hot metal. Such a nozzle is known from GB-1198112. but it seems not to have been in practical use. A possible cause may be that there will be a subpressure in the middle of the annular jet which tends to hold the jet together so that there will not be the wide hot spot that is desired. It is an object of the invention to provide for a method and a nozzle that will permit a diverging annular jet. It is other objects to provide for an adjustable annular nozzle and to provide for an adjustable annular nozzle that can create both a tight jet and a diverging jet. The invention will be described with reference to the accompanying drawings that show three annular nozzles in accordance with the invention. Figure 1 is an end view of a top blowing nozzle and Figure 2 is a section taken along the line 2-2 in Figure 1. Figure 3 is an end view of another nozzle and Figure 4 is a section taken along the line 4-4 in Figure 3. Figure 5 is an end view of still another nozzle and Figure 6 is a section taken along the line 6-6 in Figure 5. The nozzle shown in the Figures 1 and 2 comprises an outer body 11 and a central body 12 which form a slot 23 between them. The outer body 11 is arranged to be soldered to the outer and inner tubes 13. 14 of an oxygen lance. In the annular space between the tubes 13 and 14 there is an intermediate tube 15 around which cooling water is circulated in a conventional manner. The central body 12 is fixed to a rod 17 by being screwed to it or soldered to it. The rod 17 extends through the lance. The outer body 11 of the nozzle has a conical opening 18 and the central body 12 of the nozzle is substantially conical and it has six axial lands or keys 19, with parallell sides. that fit the conical opening 18. The nozzle is formed as a supersonic nozzle. The keys 19 divide the slot 23 into six parts which results in holes in the annular jet at the exit of the nozzle. Ambient gas flows in through these holes and fills out the subpressure that otherwise would occur close to the central body 12 and prevent the jet from diverging conically. These holes in the jet are filled and the jet is completely annular when it hits the melt. In Figures 3 and 4, an alternative embodiment is shown in which the nozzle is adjustable. The same reference numerals are used as in Figures 1 and 2 for corresponding details. The outer body 11 of the nozzle has three grooves 22 in its conical surface 18 and the central body 12 has three axial lands or keys 19 that fit in the grooves 22. The grooves 22 permit axial adjustment of the central body 12 by means of the rod 17 so that the width of the slot 23 between the outer and inner bodies 11, 12 can be varied. The slot 23 is thus divided into three parts. The flow regulation can suitably by carried out with a flow regulator in the conduit that leads to the nozzle and the pressure in the conduit can be adjusted by adjustment of the slot width for control of the jet velocity. As a result, the flow regulation will be independent of the axial thermal expansion of the lance and its rod 17. The relation between the flow rate and the pressure of the oxygen blast can thus be varied during the refining process, and the wide target area will be maintained. The grooves 22 can alternatively be in the central body 12 and the keys 19 on the outer body 11. In Figures 5 and 6 another alternative embodiment is shown. Its central body 12 has no lands. Instead, its outer body 11 has two lands or bulbs 19 that block only the exit part of the slot 23. Thus. the slot 23 is divided into two parts with intermediate blockings 19. This nozzle will give a wide annular hot spot on the melt as do the previous embodiments. However. when the central body 12 is displaced inwardly by means of the rod 17, there will be no disruptions in the annular slot 23 and thus. no disruptions in the annular flow exiting the nozzle. As a result. there will be a subpressure in the centre of the annular jet and the jet will contract and give a small hot spot on the melt. This nozzle makes it possible to impinge on the metal bath with a wide annular low velocity jet and with a narrow high velocity jet during various phases of the same blowing operation. As an alternative to forming holes in the jet for counteracting a subpressure against the central body 12, gas can be supplied from the end of the lance through the rod 17 and the central body 12. The gas flow supplied in this way must probably be of the same order of magnitude as the flow through the nozzle, and the illustrated embodiment is preferable. A combination of holes in the jet and a gas supply through the rod 17 and the central body 12 is also possible, and may be advantageous. A tubeformed rod 17 can be used also for supplying pulverulent material suspended in a gas or liquid. The nozzles and the lance described can be used in BOS (Basic Oxygen Steelmaking) and in other metallurgical processes in which a top blowing lance is used.

Claims: Claims 1 A supersonic annular nozzle for an oxygen lance for metallurgical use c h a r a c t e r i z e d by means (19) for permitting a gas supply to the interior of the formed annular jet in order to counteract a subpressure there. 2 A nozzle according to claim 1. c h a r a c t e r i z e d in that said means (19) blocks parts of the annular slot (23) of the nozzle so that the annular jet exiting the nozzle will be divided and permit ambient gas to flow to the interior of the jet. 3 A nozzle according to claim 2, c h a r a c t e r i z e d in that it comprises an outer annular body (11) and a central substantially conical body (12) which form together the annular slot of the nozzle, and keys (19) and grooves (22) in said bodies form said means for blocking parts of said annular slot (23), said central body (12) being axially displaceable so as to permit for a variable slot width, while said keys (19) is still blocking parts of the slot (23). 4 A supersonic annular nozzle for an oxygen lance for metallurgical use comprising an outer annular body (11) and a central body (12) which form together the annular slot (23) of the nozzle, c h a r act e r i z a d in that said central body (12) is displaceable with respect to said annular body (11) between a first position in which the slot (23) is divided into separate parts so that the exiting annular jet will be divided into separate parts and a second position in which the entire annular slot (23) is open so that the exiting annular jet will be without disruptions. 5 A nozzle according to claim 4. c h a r a c t e r i z e d in that said central body (12) is substantially conical and axially displaceable between its two positions and one of said bodies (11 * 12) has bulbs (19) at the exit end of said slot (23), said bulbs blocking said slot when the central body is in its first position but not when it is in its second position. 6 A method of blowing hot metal with an oxygen lance that has an annular nozzle, c h a r a c t e r i z e d in that gas is supplied to the interior of the formed annular jet in order to counteract a subpressure there. 7 A method according to claim 6 c h a r a c t e r i z e d in that parts of the annular gas flow exiting the nozzle are blocked in order to form holes in the annular jet through which ambient atmosphere can be sucked in.

Inventors: BERGMAN DAN, INOMOTO TAKEO, BERGMAN, DAN, INOMOTO, TAKEO
Applicants: BERGMAN DAN, INOMOTO TAKEO, STIFTELSEN METALLURG FORSK, BERGMAN, DAN, INOMOTO, TAKEO, MEFOS, STIFTELSEN FOER METALLURGISK FORSKNING
Application year: 1994
Main classification: F27D3
IPC codes: C21C5, F27D3